Recently, various epidemiological surveys have shown an increase in allergic diseases. Cases of pollenosis and atopic dermatitis, in particular, are increasing to such a degree that they have become a social problem. Increased allergens and changes in our environment such as air pollution, food additives and changes in dietary habits are thought to cause such an increase in cases of allergic diseases (Itoh, Sōgō rinsyō 41:3099(1992)). Current therapies for allergic diseases basically involve removing or rejecting causal allergens in combination with drug therapy, based on the severity of the symptoms or the pathogenic mechanism of each disease. Allergic reactions are classified into four types, from type I to IV, based on the causal immunoglobulin and immune cells involved. Type I to III allergies, which are called immediate allergies due to the patient's immediate allergic reaction, are immunoreactions in which humoral antibodies are involved, while type IV allergy, which is called delayed allergy, is a cell-mediated immune reaction in which sensitized lymphocytes but not antibodies are involved (Tomioka, Sōgō rinsyō 41:3103 (1992)).
Among these allergic reactions, type I and type IV allergic reactions are thought to be involved in pollenosis and atopic dermatitis, which are treated with antihistamines, basic antiallergic agents or steroids.
On the other hand, patent applications which relate to antiallergic agents using oolong tea extracts or epigallocatechin gallate in green tea have been filed (JPA HEI 10-077231, JPA HEI 10-175874, Japanese Patent No. 3023962, etc.). Flavones and their glycosides have been reported to have the effect of inhibiting histamine release from mast cells or to have an immunosuppressive effect, and are expected to be used as allergy therapies (Kubo M. et al, Chem. Pharm. Bull. 32: 5051 (1984)). However, most flavones exhibit their effects only at high doses, so that effective compounds at lower doses are highly desired.